This invention relates to a polarizing film widely used in optical products that utilize polarization such as polarizing glasses and liquid crystal displays, and polarizing composites comprising a polarizing film and lenses or sheets laminated on the polarizing film.
Polarizing lenses mounted on polarizing glasses are used to eliminate glare of light (polarized light formed when reflected obliquely from objects). Such lenses have a polarizing film laminated between glasses or plastic sheets.
A polarizing film used for such a polarizing lens is formed by stretching a thin film of e.g. polyvinyl alcohol to about three- to five-fold in length and dyeing the thus stretched film with iodine or a dichroic dye. Most polarizing films are grayish brown or grayish green in color.
Such polarizing films or lenses or sheets including polarizing films are used for, besides polarized glasses, glasses for viewing three-dimensional motion pictures, cameras, strain gauges, liquid crystal displays, show windows, TV OA monitors, illumination adjusting windows, etc. They are also used outdoors such as in orchards and fish farms, or in high-illumination environments such as in printing works.
Conventional polarizing films are dyed with e.g. iodine, so that light passing through such films, lenses and sheets contains various colors such as blue and brown originating from colorants. Such colors naturally differ from the colors perceptible to the naked eye. That is, the colors of objects seen through polarizing films, lenses or sheets are more difficult to distinguish than when seen by the naked eye.
Thus, use of polarizing films, lenses and sheets poses various problems. For example, in orchards, farmers with polarizing glasses on may have a hard time in distinguishing ripe fruits from unripe ones even when they consult color samples. Fish growers wearing polarizing glasses cannot know the real colors of colored carp and other aquarium fish. Similarly, for outdoor painters and printshop workers, the colors of objects to be sketched or print surfaces will look differently if they are seen through polarizing films, lenses or sheets.
An object of this invention is to provide a polarizing film or composite which can eliminate glare of the light reflected by an object and enables one to discriminate the color of the object as when seen by naked eye.